1 migrateexts -source 2 source_mdisk_id 2 source_mdisk_name 3 -target 4 target_mdisk_id 4 target_mdisk_name 5 -exts number_of_extents 6? -threads number_of_threads 7? -copy id 8 -vdisk 9 vdisk_id 9 vdisk_name